This invention relates to apparatus for detection of selected sound frequency signals emitted by sirens of emergency vehicles. The new apparatus may detect a selected sound frequency signal spectrum emitted by various siren or warning sound sources in an initial detection stage. When a warning sound may be detected, a signal identification stage may determine the sound signal characteristics and estimate the distance to the warning sound source.
Various types of emergency vehicle siren detection systems may be currently known that may tend to be complicated, overly elaborate or use a lot of electric power. Less complicated devices, for example, that disclosed in U.S. Pat. No. 7,245,232, issued on Jun. 17, 2007, and herein incorporated by reference, may be known. However, this type of apparatus may be susceptible to false detection of sounds thought to be warning signals. To achieve a balance for a lower power system that may not be overly complicated, a system may be needed that uses a lower power, simple warning signal detection stage with a power save signal identification stage that only has full power applied once a sound warning signal has been detected.